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I don’t usually write posts in five languages but I am exercising my mental muscles for a good reason. Researchers have found evidence that bilingualism is protective against Alzheimer’s and other dementias in old age, delaying the onset of dementia by four years as opposed to those who are monolingual.

Links between various lifestyle factors and “cognitive reserve” in later life have long been studied. Cognitive reserve refers to enhanced neural plasticity, compensatory use of alternative brain regions as well as enriched brain vasculature. Scientists at the Rotman Research Institute and the Baycrest Research Centre for Aging and the Brain have found that another lifestyle factor, bilingualism, is also protective in terms of cognitive reserve.

The researchers studied the diagnostic records of 184 patients who met the criteria for Alzheimer’s and other dementias. By interviewing patients and their families or caregivers, the researchers were able to determine that the mean age of onset of dementia in the monolingual group was 71.4 years. The mean age for the onset of dementia in the bilingual group was 75.5 years.

“There are no pharmacological interventions that are this dramatic,” says Dr. Freedman, who is Head of the Division of Neurology, and Director of the Memory Clinic at Baycrest, referring to the four-year delay in onset of symptoms for bilingual patients.

“The data show a huge protective effect,” adds co-investigator Dr. Craik, who cautioned that this is still a preliminary finding but nonetheless in line with a number of other recent findings about lifestyle effects on dementia.

The study is published in the February 2007 issue of Neuropsychologia (Vol.45, No.2) and was funded by the Canadian Institutes of Health Research.